Abstract: A magnetic field compensation winding arrangement for a cathode ray tube includes a magnetic field compensation winding positioned on the cathode ray tube to compensate for an ambient magnetic field. An operational amplifier is used for generating a magnetic field compensation current in the winding. A pair of digital-to-analog converters are used for generating a pair of signals, respectively, that are coupled to the amplifier to control the magnetic field compensation current.

Abstract: Synchronization of a horizontal deflection circuit with horizontal synchronizing signal pulses is obtained by the use of a voltage controlled oscillator (VCO) that is included in a phase-lock loop circuit (PLL). A phase-control loop circuit (PCL) includes a phase detector having a first input terminal that is responsive to an output signal of the VCO and a second input terminal that is responsive to retrace pulses of a horizontal deflection circuit output stage. A sum signal of the phase detector output signal of the PLL and a vertical rate parabola signal is formed upstream of the loop filter of the PLL. Correction of a differential pin distortion is accomplished by dynamically phase shifting the phase of an output signal of the VCO in a vertical rate parabola manner.

Abstract: A horizontal deflection circuit generates a horizontal deflection current in a deflection winding, during a trace interval and during a retrace interval of a deflection cycle. A transistor is responsive to a vertical rate parabola signal and to a negative feedback signal for producing a vertical rate parabolic modulation voltage at a collector of the transistor. A negative feedback network generates the feedback signal that is indicative of a current flowing in the transistor for increasing an output impedance at the collector of the transistor. An inductor is coupled to the collector of the transistor for producing in the inductor a modulation current to provide for side pincushion distortion correction in an East-West modulator.

Abstract: A dynamic focus voltage generator includes a source of a flyback input signal at a horizontal deflection frequency. A double integrator is responsive to the input signal for generating a parabolic periodic signal. An amplitude detector is responsive to the parabolic periodic signal for generating a control signal that is indicative of an amplitude of the parabolic periodic signal. A comparator is responsive to a signal at a reference level and to the control signal and coupled to the double integrator for regulating an amplitude of the parabolic periodic signal in a gain control negative feedback manner. A non-linear network is responsive to the parabolic periodic signal for producing a bathtub shaped output signal that is coupled to a focus electrode of a cathode ray tube.

Abstract: A horizontal deflection circuit generates a horizontal deflection current in a deflection winding, during a trace interval and during a retrace interval of a deflection cycle. A transistor is responsive to a vertical rate parabola signal and to a negative feedback signal for producing a vertical rate parabolic modulation voltage at a collector of the transistor. A negative feedback network generates the feedback signal that is indicative of a current flowing in the transistor for increasing an output impedance at the collector of the transistor. An inductor is coupled to the collector of the transistor for producing in the inductor a modulation current to provide for side pincushion distortion correction in an East-West modulator.

Abstract: Synchronization of a horizontal deflection circuit with horizontal synchronizing signal pulses is obtained by the use of a voltage controlled oscillator (VCO) that is included in a phase-lock loop circuit (PLL). A phase-control loop circuit (PCL) includes a phase detector having a first input terminal that is responsive to an output signal of the VCO and a second input terminal that is responsive to retrace pulses of a horizontal deflection circuit output stage. A sum signal of the phase detector output signal of the PLL and a vertical rate parabola signal is formed upstream of the loop filter of the PLL. Correction of a differential pin distortion is accomplished by dynamically phase shifting the phase of an output signal of the VCO in a vertical rate parabola manner.

Abstract: A dynamic focus voltage generator includes a source of a flyback input signal at a horizontal deflection frequency. A double integrator is responsive to the input signal for generating a parabolic periodic signal. An amplitude detector is responsive to the parabolic periodic signal for generating a control signal that is indicative of an amplitude of the parabolic periodic signal. A comparator is responsive to a signal at a reference level and to the control signal and coupled to the double integrator for regulating an amplitude of the parabolic periodic signal in a gain control negative feedback manner. A non-linear network is responsive to the parabolic periodic signal for producing a bathtub shaped output signal that is coupled to a focus electrode of a cathode ray tube.

Abstract: An apparatus displays pictures from sources having a plurality of horizontal frequencies. A scanning generator is operable at the plurality of frequencies and comprises an oscillator generating a signal. A divider with two selectable counts is coupled to the oscillator and divides the signal by a first count to generate a horizontal drive signal. A horizontal scanning amplifier generates a scanning signal responsive to the horizontal drive signal coupled thereto. A controller is coupled to the scanning amplifier and to the divider. In response to selecting another of the plurality of frequencies, the controller monitors the scanning signal and responsive to its presence inhibits selection of a second of the selectable counts. In the absence of the scanning signal the controller enables selection of the second of selectable counts and the divider generates a horizontal drive signal representative of the another one of the plurality of horizontal scanning frequencies.

Abstract: A vertical deflection amplifier drives a vertical deflection coil according to a ramp input signal and has a current sensing resistor providing a feedback signal. The vertical deflection coil is subject to crosstalk or excitation by a horizontal deflection coil. A compensation network is coupled between a source of the horizontal deflection signal and the current sense resistor, and has a network that produces a corrective current in the current sense resistor to substantially cancel horizontal rate crosstalk component from the feedback signal.

Abstract: A video imaging apparatus includes a source of a blanking signal that is indicative when a blanking interval occurs in a video signal. A delay circuit including a horizontal line counter is responsive to the blanking signal and to a signal at the horizontal rate for delaying the blanking signal by a multiple number of horizontal periods to generate a delayed signal. A dynamic focus voltage generator includes a switch responsive to the delayed signal for applying a dynamic focus voltage to a focus electrode, when the switch is at a first state, and for disabling the application of the dynamic focus voltage, when the switch is at a second state. An end time of the interval, during which the dynamic focus voltage is disabled, is determined in accordance with an output signal of the counter.

Abstract: A video display apparatus for pictures from broadcast sources having standard or high definition, which may also display computer generated images. To display this range of sources a horizontal frequency signal generator is selectably operable at a plurality of frequencies. The generator comprises an oscillator controlled for synchronized oscillation at a plurality of horizontal frequencies. A source of synchronizing pulses is coupled to an input of a phase detector which has another input coupled to the oscillator. The phase detector generates an output signal representative of a phase difference between the inputs. A processor is coupled to the phase detector for processing the output signal and generating a control signal for controlling the oscillator. The processor gain is controlled responsive to selected ones of the plurality of frequencies.

Abstract: A video display apparatus displays pictures from broadcast sources of standard or high definition pictures and may also display computer generated images. To display these sources a horizontal deflection signal generator is operable at a plurality of frequencies. The deflection signal generator comprises a controlled oscillator generating a output signal. A divider divides the output signal to form a horizontal frequency signal. A phase detector receives the horizontal frequency signal and a synchronizing signal and generates an analog signal for coupling to the oscillator. A digital to analog converter generates a voltage from a digital data word and couples the voltage to the oscillator. The voltage determines a center frequency of the oscillator and the analog signal controls the oscillator to synchronize with the synchronizing signal.

Abstract: A circuit for providing an output voltage to a pincushion modulator circuit. The circuit includes an amplifier having an input for receiving an input signal. The amplifier amplifies the input signal to produce the output voltage at an output of the amplifier which is coupled to an input of the pincushion modulator circuit. A compensation path eliminates instability at frequencies above a first frequency caused by interaction between the amplifier and the pincushion modulator circuit.

Abstract: An arrangement for reproducing a composite blanking or sync signal includes a vertical deflection circuit having a supply boost stage. A first pulse voltage at a vertical rate is derived from an output signal of the boost stage. The vertical rate, first pulse voltage is coupled to a base terminal of an emitter follower via a voltage divider for producing a leading edge of an output pulse voltage of the emitter follower. The vertical rate first pulse voltage is also coupled via an R-C network to a regenerative switch. The regenerative switch is coupled to the base terminal of the emitter follower for producing a trailing edge of the output pulse voltage of the emitter follower. The trailing edge is produced after a predetermined interval has elapsed from the leading edge. The output pulse voltage of the emitter follower is combined with a horizontal rate pulse voltage for producing the composite sync signal.

Abstract: A bus controlled pulse modulator receives a digitally coded signal and generates a pulse-width modulated signal. The pulse-width modulated signal is coupled to a base electrode of a non-committed or open collector transistor. The transistor switches with a controlled duty cycle. The collector of the transistor is coupled to an inverting input terminal of an amplifier via a resistor. The amplifier produces a compensation current in a tilt compensation coil. The voltage at the inverting input terminal is maintained constant in closed loop operation. The constant voltage produces a magnitude of a collector current in the transistor that is unaffected by the duty cycle of the pulse-width modulated signal. The compensation current thereby varies linearly with the duty cycle.

Abstract: In a vertical sawtooth generator, an end time of a retrace portion of a vertical sawtooth signal is controlled by an output signal of a comparator. The comparator has a first input terminal that is responsive to a reference voltage and a second input terminal that is responsive to the sawtooth signal. The reference voltage is coupled to an input terminal of an amplifier of an integrator that generates the sawtooth signal. Any disturbance signal component in the reference voltage is super-imposed on the sawtooth signal. Because the same disturbance signal component is developed simultaneously in both input terminals of the comparator, a high degree of common mode rejection is provided with respect to the disturbance signal component.